#include <vector>
#include <unordered_map>
#include <iostream>
#include <ranges>
#include <cstdlib>
#include <cmath>

int main() {
  std::vector<int> left_list;
  std::unordered_map<int, int> right_list;
  int left, right;
  while (std::cin >> left >> right) {
    left_list.emplace_back(left);
    right_list[right]++;
  }
  int score = 0;
  for(auto left_elem : left_list) {
    score += left_elem * right_list[left_elem];
  }
  std::cout << score << std::endl;
  return EXIT_SUCCESS;
}